5,108 research outputs found

    Influence of Strip-Mining on the Mortality of a Wetland Caddisfly, \u3ci\u3eLimnephilus Indivisus\u3c/i\u3e (Trichoptera: Limnephilidae).

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    A coal mine about 2.2 km upstream from Stillfork Swamp Nature Preserve, Carroll Co., Ohio was suspected of causing a reduction in Limnephilus indivisus caddisflies in the south half of the preserve. Second instar L. indivisus larvae collected from the south half of the preserve and from two control areas were reared in cages at the site of collection and at the other two sites in a replicated experiment. Elevated total dissolved solids in water samples from within rearing enclosures displayed strong correlation (r2 = 0.864) with increased mortality when compared to larvae reared in unaffected areas. This investigation suggests that larvae of L. indivisus are useful in biomonitoring of wetlands impacted by acid-mine drainage, and potentially other perturbations

    Dynamics of clade diversification on the morphological hypercube

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    Understanding the relationship between taxonomic and morphological changes is important in identifying the reasons for accelerated morphological diversification early in the history of animal phyla. Here, a simple general model describing the joint dynamics of taxonomic diversity and morphological disparity is presented and applied to the data on the diversification of blastozoans. I show that the observed patterns of deceleration in clade diversification can be explicable in terms of the geometric structure of the morphospace and the effects of extinction and speciation on morphological disparity without invoking major declines in the size of morphological transitions or taxonomic turnover rates. The model allows testing of hypotheses about patterns of diversification and estimation of rates of morphological evolution. In the case of blastozoans, I find no evidence that major changes in evolutionary rates and mechanisms are responsible for the deceleration of morphological diversification seen during the period of this clade's expansion. At the same time, there is evidence for a moderate decline in overall rates of morphological diversification concordant with a major change (from positive to negative values) in the clade's growth rate.Comment: 8 pages, Latex, 2 postscript figures, submitted to Proc.R.Soc.Lond.

    The snail-killing flies of Alaska (Diptera: Sciomyzidae)

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    Information is given on the geographic distribution, habitat preferences, larval foods, and immature stages for 57 species of 9 genera of Sciomyzidae known to occur in Alaska. An illustrated key to adults is included. Alaska as a habitat for sciomyzid flies is discussed, and information on feeding habits of the larvae is summarized

    A Three-dimensional Deformable Brain Atlas for DBS Targeting. I. Methodology for Atlas Creation and Artifact Reduction.

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    BackgroundTargeting in deep brain stimulation (DBS) relies heavily on the ability to accurately localize particular anatomic brain structures. Direct targeting of subcortical structures has been limited by the ability to visualize relevant DBS targets.Methods and resultsIn this work, we describe the development and implementation, of a methodology utilized to create a three dimensional deformable atlas for DBS surgery. This atlas was designed to correspond to the print version of the Schaltenbrand-Bailey atlas structural contours. We employed a smoothing technique to reduce artifacts inherent in the print version.ConclusionsWe present the methodology used to create a three dimensional patient specific DBS atlas which may in the future be tested for clinical utility

    Apollo SM-LM RCS engine development program summary report, volume 4 Final report

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    Development, performance, and production acceptance tests for Apollo R-4D engin

    Apollo SM-LM RCS engine development program summary report, volume 3 Final report

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    R-4D engine attitude control and performance under launch and space stresse
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